This invention pertains to impact absorbers to protect humans, animals, equipment and cargo from injury or damage during transportation or other movement in which there is danger of destructive impact with external objects, and more particularly to protective structures for humans against impacts that otherwise would prove injurious or fatal.
Materials and devices intended to protect delicate or sensitive equipment and body parts from damage or injury caused by impact are as old as human history. Shields, armor and pads were worn to protect soldiers and horses from blows and projectiles. Guards and pads were worn to protect players from impact injury during games and training. These protective materials and devices all use the same dual function approach to protect the delicate body from injury: prevent penetration of the soft body by hard objects, and distribute the impact over a larger area to avoid concentration of the blow in one small area that would be damaged/injured by the blow.
More modern approaches to the same problem have used the same dual function approach, while seeking to enhance a third function implicit in the earlier approaches, specifically, a gradual deceleration of the impacting object. Sports gear, such as football helmets and shoulder pads, are good examples of the classic approach and its application of the deceleration function. A hard shell presents an exterior that deflects high energy objects and/or distributes the impact therefrom to an underlying pad that further distributes the impact force over a wider area. The pad may be made with a material having a spring rate which allows the impacting force to be applied at a gradually increasing rate to the impacted body so that the body is accelerated, or the object is decelerated, at a rate that minimizes damage. Often, in bicycle helmets, for example, the pad is a foam material that offers some protection but must be replaced after an impact because the foam becomes permanently compressed and loses some of its impact protection qualities after the first impact.
Regrettably, the materials used in such impact protectors do little or nothing to absorb the energy of the impact and merely distribute the impact over a larger area or time. The full impact energy is usually delivered to the xe2x80x9cprotectedxe2x80x9d body in time/area distributed form that may still exceed the limits of the body to absorb impact.
Dampers having a spring and a hydraulic ported cylinder, most commonly found in automobile xe2x80x9cshock absorbersxe2x80x9d, do absorb energy, but the size and cost of such dampers precludes their use in many applications, and they have a limited life because of short seal life and hydraulic fluid leakage.
Thus, the art of impact protection has long needed a simple, light-weight system that performs all three protective functions as well or better than existing impact protectors: protecting against penetration, distributing the force over a wide area, and decelerating the impacting body and accelerating the body gradually. Ideally, such a new system would also absorb impact energy and convert it from mechanical or kinetic energy to heat. Finally, such an ideal system would be inexpensive, small in size and weight, easily restored or self-restoring, and extremely durable and long lasting.